Methods of degrading filter cakes in subterranean formations Patent Grant Munoz, Jr. January 19, 2 [Halliburton Energy Services, Inc.]

Methods of degrading filter cakes in subterranean formations

Munoz, Jr. January 19, 2

Patent Grant 7648946

U.S. patent number 7,648,946 [Application Number 10/991,228] was granted by the patent office on 2010-01-19 for methods of degrading filter cakes in subterranean formations. This patent grant is currently assigned to Halliburton Energy Services, Inc.. Invention is credited to Trinidad Munoz, Jr..

United States Patent	7,648,946
Munoz, Jr.	January 19, 2010

**Please see images for: ( Certificate of Correction ) **

Methods of degrading filter cakes in subterranean formations

Abstract

Methods of degrading filter cakes in subterranean formations are provided. An example of a method is a method of drilling a well bore in a subterranean formation. Another example of a method is a method of degrading a filter cake in a subterranean formation, the filter cake comprising an inorganic portion and an organic portion, and having been established in the formation by a well drill-in and servicing fluid that comprises a delayed-release acid component. An example of a composition is a well drill-in and servicing fluid.

Inventors:	Munoz, Jr.; Trinidad (Duncan, OK)
Assignee:	Halliburton Energy Services, Inc. (Duncan, OK)
Family ID:	35985183
Appl. No.:	10/991,228
Filed:	November 17, 2004

Prior Publication Data


	Document Identifier	Publication Date
	US 20060105918 A1	May 18, 2006

Current U.S. Class:	507/110; 507/114; 507/112; 175/65; 166/270; 166/268; 166/244.1
Current CPC Class:	C09K 8/52 (20130101); C09K 8/02 (20130101); C09K 2208/18 (20130101)
Current International Class:	E21B 43/16 (20060101); C09K 8/035 (20060101); C09K 8/08 (20060101)
Field of Search:	;507/110,112,114 ;166/244.1,268,270 ;175/65

References Cited [Referenced By]

U.S. Patent Documents


2238671	April 1941	Woodhouse
2703316	March 1955	Palmer
3173484	March 1965	Huitt et al.
3195635	July 1965	Fast
3272650	September 1966	MacVittie
3302719	February 1967	Fischer
3364995	January 1968	Atkins et al.
3366178	January 1968	Malone et al.
3455390	July 1969	Gallus
3784585	January 1974	Schmitt et al.
3819525	June 1974	Hattenbrun
3828854	August 1974	Templeton et al.
3836465	September 1974	Rhudy et al.
3868998	March 1975	Lybarger et al.
3912692	October 1975	Casey et al.
3948672	April 1976	Harnsberger
3955993	May 1976	Curtice et al.
3960736	June 1976	Free et al.
3968840	July 1976	Tate
3986355	October 1976	Klaeger
3998272	December 1976	Maly
3998744	December 1976	Arnold et al.
4010071	March 1977	Colegrove
4068718	January 1978	Cooke, Jr. et al.
4169798	October 1979	DeMartino
4172066	October 1979	Zweigle et al.
4261421	April 1981	Watanabe
4265673	May 1981	Pace et al.
4299825	November 1981	Lee
4387769	June 1983	Erbstoesser et al.
4460052	July 1984	Gockel
4470915	September 1984	Conway
4498995	February 1985	Gockel
4502540	March 1985	Byham
4506734	March 1985	Nolte
4521316	June 1985	Sikorski
4526695	July 1985	Erbstoesser et al.
4632876	December 1986	Laird et al.
4694905	September 1987	Armbruster
4715967	December 1987	Bellis
4716964	January 1988	Erbstoesser et al.
4767706	August 1988	Levesque et al.
4772346	September 1988	Anderson et al.
4785884	November 1988	Armbruster
4793416	December 1988	Mitchell
4797262	January 1989	Dewitz
4809783	March 1989	Hollenbeck et al.
4817721	April 1989	Pober
4822500	April 1989	Dobson, Jr. et al.
4829100	May 1989	Murphey et al.
4836940	June 1989	Alexander
4843118	June 1989	Lai et al.
4848467	July 1989	Cantu et al.
4863980	September 1989	Cowan et al.
4886354	December 1989	Welch et al.
4894231	January 1990	Moreau et al.
4957165	September 1990	Cantu et al.
4961466	October 1990	Himes et al.
4986353	January 1991	Clark et al.
4986354	January 1991	Cantu et al.
4986355	January 1991	Casad et al.
5034139	July 1991	Reid et al.
5082056	January 1992	Tackett, Jr.
5142023	August 1992	Gruber et al.
5152781	October 1992	Tang et al.
5161615	November 1992	Hutchins et al.
5203834	April 1993	Hutchins et al.
5213446	May 1993	Dovan
5216050	June 1993	Sinclair
5247059	September 1993	Gruber et al.
5249628	October 1993	Surjaatmadja
5251697	October 1993	Shuler
5295542	March 1994	Cole et al.
5304620	April 1994	Holtmyer et al.
5314031	May 1994	Hale et al.
5325923	July 1994	Surjaatmadja et al.
5330005	July 1994	Card et al.
5359026	October 1994	Gruber
5360068	November 1994	Sprunt et al.
5363916	November 1994	Himes et al.
5373901	December 1994	Norman et al.
5386874	February 1995	Laramay et al.
5396957	March 1995	Surjaatmadja et al.
5402846	April 1995	Jennings, Jr. et al.
5439055	August 1995	Card et al.
5460226	October 1995	Lawton et al.
5464060	November 1995	Hale et al.
5475080	December 1995	Gruber et al.
5484881	January 1996	Gruber et al.
5487897	January 1996	Polson et al.
5492177	February 1996	Yeh et al.
5496557	March 1996	Feijen et al.
5497830	March 1996	Boles et al.
5499678	March 1996	Surjaatmadja et al.
5501276	March 1996	Weaver et al.
5505787	April 1996	Yamaguchi
5512071	April 1996	Yam et al.
5536807	July 1996	Gruber et al.
5555936	September 1996	Pirri et al.
5591700	January 1997	Harris et al.
5594095	January 1997	Gruber et al.
5602083	February 1997	Gabrysch et al.
5604186	February 1997	Hunt et al.
5607905	March 1997	Dobson, Jr. et al.
5613558	March 1997	Dillenbeck
5670473	September 1997	Scepanski
5697440	December 1997	Weaver et al.
5698322	December 1997	Tsai et al.
5723416	March 1998	Liao
5765642	June 1998	Surjaatmadja
5783527	July 1998	Dobson, Jr. et al.
5791415	August 1998	Nguyen et al.
5799734	September 1998	Norman et al.
5833000	November 1998	Weaver et al.
5849401	December 1998	El-Afandi et al.
5853048	December 1998	Weaver et al.
5893416	April 1999	Read
5908073	June 1999	Nguyen et al.
5916849	June 1999	House
5924488	July 1999	Nguyen et al.
5964291	October 1999	Bourne et al.
5977030	November 1999	House
5979557	November 1999	Card et al.
5996693	December 1999	Heathman
6004400	December 1999	Bishop et al.
6024170	February 2000	McCabe et al.
6028113	February 2000	Scepanski
6047772	April 2000	Weaver et al.
6110875	August 2000	Tjon-Joe-Pin et al.
6114410	September 2000	Betzold
6123159	September 2000	Brookey et al.
6123965	September 2000	Jacob et al.
6131661	October 2000	Conner et al.
6135987	October 2000	Tsai et al.
6143698	November 2000	Murphey et al.
6148917	November 2000	Brookey et al.
6162766	December 2000	Muir et al.
6169058	January 2001	Le et al.
6172011	January 2001	Card et al.
6189615	February 2001	Sydansk
6202751	March 2001	Chatterji et al.
6209643	April 2001	Nguyen et al.
6209646	April 2001	Reddy et al.
6214773	April 2001	Harris et al.
6242390	June 2001	Mitchell et al.
6260622	July 2001	Blok et al.
6291013	September 2001	Gibson et al.
6300286	October 2001	Dobson, Jr. et al.
6302209	October 2001	Thompson et al.
6308788	October 2001	Patel et al.
6311773	November 2001	Todd et al.
6323307	November 2001	Bigg et al.
6326458	December 2001	Gruber et al.
6328105	December 2001	Betzold
6330917	December 2001	Chatterji et al.
6357527	March 2002	Norman et al.
6364945	April 2002	Chatterji et al.
6380138	April 2002	Ischy et al.
6387986	May 2002	Moradi-Araghi et al.
6390195	May 2002	Nguyen et al.
6394185	May 2002	Constien
6422314	July 2002	Todd et al.
6422326	July 2002	Brookey et al.
6432155	August 2002	Swazey et al.
6454003	September 2002	Chang et al.
6485947	November 2002	Rajgarhia et al.
6488763	December 2002	Brothers et al.
6494263	December 2002	Todd
6508305	January 2003	Brannon et al.
6509301	January 2003	Vollmer et al.
6527051	March 2003	Reddy et al.
6554071	April 2003	Reddy et al.
6566310	May 2003	Chan
6569814	May 2003	Brady et al.
6578630	June 2003	Simpson et al.
6599863	July 2003	Palmer et al.
6667279	December 2003	Hessert et al.
6669771	December 2003	Tokiwa et al.
6681856	January 2004	Chatterji et al.
6686328	February 2004	Binder
6691780	February 2004	Nguyen et al.
6702023	March 2004	Harris et al.
6710019	March 2004	Sawdon et al.
6716797	April 2004	Brookey
6737385	May 2004	Todd et al.
6761218	July 2004	Nguyen et al.
6763888	July 2004	Harris et al.
6764981	July 2004	Eoff et al.
6793018	September 2004	Dawson et al.
6793730	September 2004	Reddy et al.
6806235	October 2004	Mueller et al.
6817414	November 2004	Lee
6818594	November 2004	Freeman et al.
6837309	January 2005	Boney et al.
6883608	April 2005	Parlar et al.
6896058	May 2005	Munoz, Jr. et al.
6904971	June 2005	Brothers et al.
6949491	September 2005	Cooke, Jr.
6959767	November 2005	Horton et al.
6978838	December 2005	Parlar et al.
6981552	January 2006	Reddy et al.
6983801	January 2006	Dawson et al.
6987083	January 2006	Phillippi et al.
6997259	February 2006	Nguyen
7007752	March 2006	Reddy et al.
7021377	April 2006	Todd et al.
7032663	April 2006	Nguyen
7036586	May 2006	Roddy et al.
7036587	May 2006	Munoz, Jr. et al.
7044220	May 2006	Nguyen et al.
7044224	May 2006	Nguyen
7063151	June 2006	Nguyen et al.
7066258	June 2006	Justus et al.
7069994	July 2006	Cooke, Jr.
7080688	July 2006	Todd et al.
7093664	August 2006	Todd et al.
7096947	August 2006	Todd et al.
7101829	September 2006	Guichard et al.
7131491	November 2006	Blauch et al.
7140438	November 2006	Frost et al.
7147067	December 2006	Getzalf et al.
7151077	December 2006	Prud'homme et al.
7156174	January 2007	Roddy et al.
7165617	January 2007	Lord et al.
7168489	January 2007	Frost et al.
7172022	February 2007	Reddy et al.
7178596	February 2007	Blauch et al.
7195068	March 2007	Todd
7204312	April 2007	Roddy et al.
7219731	May 2007	Sullivan et al.
7261156	August 2007	Nguyen et al.
7264051	September 2007	Nguyen et al.
7299876	November 2007	Lord et al.
7303014	December 2007	Reddy et al.
7306037	December 2007	Nguyen et al.
7322412	January 2008	Badalamenti et al.
7353876	April 2008	Savery et al.
7353879	April 2008	Todd et al.
7413017	August 2008	Nguyen et al.
7448450	November 2008	Luke et al.
7455112	November 2008	Moorehead et al.
7461697	December 2008	Todd et al.
7475728	January 2009	Pauls et al.
7484564	February 2009	Welton et al.
7497258	March 2009	Savery et al.
7497278	March 2009	Schriener et al.
7506689	March 2009	Surjaatmadja et al.
2001/0016562	August 2001	Muir et al.
2002/0036088	March 2002	Todd
2002/0119169	August 2002	Angel et al.
2002/0125012	September 2002	Dawson et al.
2003/0054962	March 2003	England et al.
2003/0060374	March 2003	Cooke, Jr.
2003/0114314	June 2003	Ballard et al.
2003/0130133	July 2003	Vollmer
2003/0147965	August 2003	Bassett et al.
2003/0188766	October 2003	Banerjee et al.
2003/0230407	December 2003	Vijn et al.
2003/0234103	December 2003	Lee et al.
2004/0014606	January 2004	Parlar et al.
2004/0014607	January 2004	Sinclair et al.
2004/0040706	March 2004	Hossaini et al.
2004/0055747	March 2004	Lee
2004/0070093	April 2004	Mathiowitz et al.
2004/0094300	May 2004	Sullivan et al.
2004/0099416	May 2004	Vijn et al.
2004/0106525	June 2004	Willbert et al.
2004/0138068	July 2004	Rimmer et al.
2004/0152601	August 2004	Still et al.
2004/0152602	August 2004	Boles
2004/0162386	August 2004	Altes et al.
2004/0170836	September 2004	Bond et al.
2004/0214724	October 2004	Todd et al.
2004/0216876	November 2004	Lee
2004/0231845	November 2004	Cooke, Jr.
2004/0261993	December 2004	Nguyen
2004/0261995	December 2004	Nguyen et al.
2004/0261996	December 2004	Munoz, Jr. et al.
2004/0261999	December 2004	Nguyen
2005/0006095	January 2005	Justus et al.
2005/0028976	February 2005	Nguyen
2005/0034861	February 2005	Saini et al.
2005/0034865	February 2005	Todd et al.
2005/0059556	March 2005	Munoz, Jr. et al.
2005/0059557	March 2005	Todd et al.
2005/0059558	March 2005	Blauch et al.
2005/0103496	May 2005	Todd et al.
2005/0126785	June 2005	Todd
2005/0183741	August 2005	Surjaatmadja et al.
2005/0205266	September 2005	Todd et al.
2005/0252659	November 2005	Sullivan et al.
2005/0272613	December 2005	Cooke, Jr.
2005/0277554	December 2005	Blauch et al.
2006/0016596	January 2006	Pauls et al.
2006/0032633	February 2006	Nguyen
2006/0046938	March 2006	Harris et al.
2006/0048938	March 2006	Kalman
2006/0065397	March 2006	Nguyen et al.
2006/0105917	May 2006	Munoz
2006/0169448	August 2006	Savery et al.
2006/0169452	August 2006	Savery et al.
2006/0169453	August 2006	Savery et al.
2006/0172893	August 2006	Todd et al.
2006/0205608	September 2006	Todd
2006/0243449	November 2006	Welton et al.
2006/0247135	November 2006	Welton et al.
2006/0254774	November 2006	Saini et al.
2006/0283597	December 2006	Schriener et al.
2007/0042912	February 2007	Welton et al.
2007/0049501	March 2007	Saini et al.
2007/0066492	March 2007	Funkhouser et al.
2007/0066493	March 2007	Funkhouser et al.
2007/0078063	April 2007	Munoz, Jr.
2007/0078064	April 2007	Munoz et al.
2007/0235190	October 2007	Lord et al.
2007/0238623	October 2007	Saini et al.
2007/0281868	December 2007	Pauls et al.
2008/0026955	January 2008	Munoz et al.
2008/0026959	January 2008	Munoz et al.
2008/0026960	January 2008	Munoz et al.
2008/0027157	January 2008	Munoz et al.
2008/0070810	March 2008	Mang
2008/0139415	June 2008	Todd et al.
2008/0169102	July 2008	Carbajal et al.
2009/0062157	March 2009	Munoz et al.

Foreign Patent Documents


0 510 762	Apr 1992	EP
0 672 740	Mar 1995	EP
0 672 740	Sep 1995	EP
0 879 935	Nov 1998	EP
0 879 935	Oct 1999	EP
1 413 710	Apr 2004	EP
2004181820	Jul 2004	JP
WO 93/15127	Aug 1993	WO
WO 94/07949	Apr 1994	WO
WO 94/08078	Apr 1994	WO
WO 94/08090	Apr 1994	WO
WO 95/09879	Apr 1995	WO
WO 97/11845	Apr 1997	WO
WO 99/27229	Jun 1999	WO
WO 00/57022	Sep 2000	WO
WO 01/02698	Jan 2001	WO
WO 01/87797	Nov 2001	WO
WO 01/94744	Dec 2001	WO
WO 02/55843	Jan 2002	WO
WO 02/12674	Feb 2002	WO
WO 03/027431	Apr 2003	WO
WO 03/027431	Apr 2003	WO
WO 2004/007905	Jan 2004	WO
WO 2004/037946	May 2004	WO
WO 2004/038176	May 2004	WO
WO 2004/038176	May 2004	WO

Other References

Simmons, et al., Poly(phenyllactide): Synthesis, Characterization, and Hydrolytic Degradation, Biomacromolecules, vol. 2, No. 2, 2001 (pp. 658-663). cited by other .
Yin, et al., Preparation and Characterization of Substituted Polylactides, American Chemical Society, vol. 32, No. 23, 1999 (pp. 7711-7718). cited by other .
Yin, et al., Synthesis and Properties of Polymers Derived form Substituted Lactic Acids, American Chemical Society, Ch. 12, 2001 (pp. 147-159). cited by other .
Cantu, et al, Laboratory and Field Evaluation of a Combined Fluid-Loss-Control Additive and Gel Breaker for Fracturing Fluids, SPE 18211, Society of Petroleum Engineers, 1990. cited by other .
Love, et al, Selectively Placing Many Fractures in Openhole Horizontal Wells Improves Production, SPE 50422, Society of Petroleum Engineers, 1998. cited by other .
McDaniel, et al, Evolving New Stimulation Process Proves Highly Effective in Level I Dual-Lateral Completion, SPE 78697, Society of Petroleum Engineers, 2002. cited by other .
Albertsson, et al, Aliphatic Polyesters: Systhesis, Properties and Applications, Advances in Polymer Science, vol. 157, 2002. cited by other .
Dechy-Cabaret, et al, Controlled Ring-Opening Polymerization of Lactide and Glycolide, American Chemical Society, Chemical Reviews, A-Z, AA-AD, received 2004. cited by other .
Funkhouser, et al, Synthetic Polymer Fracturing Fluid for High-Temperature Applications, SPE 80236, Society of Petroleum Engineers, 2003. cited by other .
Chelating Agents, Encyclopedia of Chemical Technology, vol. 5 (764-795). cited by other .
Vichaibun, et al, A New Assay for the Enzymatic Degradation of Polylactic Acid, Short Report, ScienceAsia, vol. 29, 2003 (pp. 297-300). cited by other .
Halliburton, SurgiFrac.sup.SM Service, A Quick and Cost-Effective Method to Help Boost Production From Openhole Horizontal Completions, Halliburton Communications, HO3297, 2002. cited by other .
Halliburton, Cobra Frac.sup.SM Service, Coiled Tubing Fracturing--Cost-Effective Method for Stimulating Untapped Reserves, HO2319R, Halliburton Energy Services, 2000. cited by other .
Halliburton, CobraJet Frac.sup.SM Service, Cost-effective Technology That Can Help Reduce Cost Per BOE Produced, Shorten Cycle Time and Reduce Capex, Halliburton Communications. cited by other .
Blauch, et al, Aqueous Tackifier and Methods of Controlling Particulates, U.S. Appl. No. 10/864,061, filed Jun. 9, 2004. cited by other .
Blauch, et al, Aqueous-Based Tackifier Fluids and Methods of Use, U.S. Appl. No. 10/864,618, filed Jun. 9, 2004. cited by other .
U.S. Appl. No. 10/650,101, filed Aug. 26, 2003, Todd, et al. cited by other .
U.S. Appl. No. 10/655,883, filed Sep. 5, 2003, Nguyen. cited by other .
U.S. Appl. No. 10/661,173, filed Sep. 11, 2003, Todd, et al. cited by other .
U.S. Appl. No. 10/664,126, filed Sep. 17, 2003, Todd, et al. cited by other .
Y. Chiang et al.: "Hydrolysis of Ortho Esters: Further Investigation of the Factors Which Control the Rate-Determining Step," Engineering Information Inc., NY, NY, vol. 105, No. 23 (XP-002322842), Nov. 16, 1983. cited by other .
M. Ahmad, et al.: "Ortho Ester Hydrolysis: Direct Evidence for a Three-Stage Reaction Mechanism, "Engineering Information Inc., NY, NY, vol . 101, No. 10 (XP-002322843), May 9, 1979. cited by other .
Skrabal et al., The Hydrolysis Rate of Orthoformic Acid Ethyl Ether, Chemical Institute of the University of Graz, pp. 1-38, Jan. 13, 1921. cited by other .
Heller, et al., Poly(ortho esters)--From Concept To Reality, Biomacromolecules, vol. 5, No. 5, 2004 (pp. 1625-1632), May 9, 1979. cited by other .
Schwach-Abdellaoui, et al., Hydrolysis and Erosion Studies of Autocatalyzed Poly(ortho esters) Containing Lactoyl-Lactyl Acid Dimers, American Chemical Society, vol. 32, No. 2, 1999 (pp. 301-307). cited by other .
Ng, et al., Synthesis and Erosion Studies of Self-Catalyzed Poly(ortho ester)s, American Chemical Society, vol. 30, No. 4, 1997 (pp. 770-772). cited by other .
Ng, et al., Development Of A Poly(ortho ester) prototype With A Latent Acid In The Polymer Backbone For 5-fluorouracil Delivery, Journal of Controlled Release 65 (2000), (pp. 367-374). cited by other .
Rothen-Weinhold, et al., Release of BSA from poly(ortho ester) extruded thin strands, Journal of Controlled Release 71, 2001, (pp. 31-37). cited by other .
Heller, et al., Poly(ortho ester)s--their development and some recent applications, European Journal of Pharmaceutics and Biopharmaceutics, 50, 2000, (pp. 121-128). cited by other .
Heller, et al., Poly(ortho esters); synthesis, characterization, properties and uses, Advanced Drug Delivery Reviews, 54, 2002, (pp. 1015-1039). cited by other .
Heller, et al., Poly(ortho esters) For The Pulsed And Continuous Delivery of Peptides And Proteins, Controlled Release and Biomedical Polymers Department, SRI International, (pp. 39-46). cited by other .
Zignani, et al., Subconjunctival biocompatibility of a viscous bioerodable poly(ortho ester), J. Biomed Mater Res, 39, 1998, pp. 277-285. cited by other .
Toncheva, et al., Use of Block Copolymers of Poly(Ortho Esters) and Poly (Ethylene Glycol), Journal of Drug Targeting, 2003, vol. 11(6), pp. 345-353. cited by other .
Schwach-Abdellaoui, et al., Control of Molecular Weight For Auto-Catalyzed Poly(ortho ester) Obtained by Polycondensation Reaction, International Journal of Polymer Anal Charact., 7: 145-161, 2002, pp. 145-161. cited by other .
Heller, et al., Release of Norethindrone from Poly(Ortho Esters), Polymer Engineering and Science, Mid-Aug. 1981, vol. 21, No. 11 (pp. 727-731). cited by other .
Cordes, et al., Mechanism and Catalysis for Hydrolysis of Acetals, Ketals, and Other Esters, Department of Chemistry, Indiana University, Bloomington, Indiana, Chemical Reviews, 1974, vol. 74, No. 5, pp. 581-603. cited by other .
Todd, et al., A Chemcial "Trigger" Useful for Oilfield Applications, Society of Petroleum Engineers, Inc., SPE 92709, Feb. 4, 2005. cited by other .
Written Opinion and Search Report for Application No. PCT/GB2005/004389, Mar. 24, 2006. cited by other .
Foreign communication related to a counterpart application dated Mar. 24, 2006. cited by other .
Kiyoshi Matsuyama et al, Environmentally benign formation of polymeric microspheres by rapid expansion of supercritical carbon dioxide solution with a nonsolvent, Environ Sci Technol 2001, 35, 4149-4155. cited by other .
Office Action dated Feb. 1, 2008 from U.S. Appl. No. 10/991,248, Feb. 1, 2008. cited by other .
Office Action dated Oct. 24, 2007 from U.S. Appl. No. 10/991,248, Oct. 24, 2007. cited by other .
Office Action dated Jun. 15, 2007 from U.S. Appl. No. 10/991,248, Jun. 15, 2007. cited by other .
Notice of Allowance and Notice of Allowability for U.S. Appl. No. 10/991,248, mailed Jan. 30, 2009. cited by other .
Office Action mailed Aug. 13, 2008 from U.S. Appl. No. 10/991,248. cited by other .
NatureWorks Product Bulletin entitled NatureWorks PLA Polymer 3001D, Injection Molding Process Guide, 2005. cited by other .
NatureWorks Product Bulletin entitled NatureWorks PLA Polymer 4060D, For Heat Seal Layer in Coextruded Oriented Films, 2005. cited by other .
NatureWorks article entitled NatureWorks, Crystallizing and Drying of PLA, 2005. cited by other.

Primary Examiner: Kugel; Timothy J.
Attorney, Agent or Firm: Kent; Robert A. Baker Botts LLP

Claims

What is claimed is:

1. A method of drilling a well bore in a subterranean formation, comprising: using a well drill-in and servicing fluid to drill a well bore in a subterranean formation, the well drill-in and servicing fluid comprising a base fluid, a viscosifier, a fluid loss control additive, a bridging agent, and at least one delayed-release acid component selected from the group consisting of an ortho ester and a poly(ortho ester), wherein the delayed-release acid component is present in the well drill-in and servicing fluid in an amount in the range of from about 1% to about 40% by weight; permitting the well drill-in and servicing fluid to establish a filter cake in at least a portion of the well bore; contacting the filter cake with an initiator component separate from the well drill-in and servicing fluid; and permitting the filter cake to degrade at a desired time.

2. The method of claim 1 wherein the base fluid is aqueous-based, nonaqueous-based, or a mixture thereof.

3. The method of claim 2 wherein the nonaqueous-based base fluid comprises at least one fluid selected from the group consisting of: mineral oil, a synthetic oil, an ester, and any derivative thereof.

4. The method of claim 1 wherein the viscosifier comprises at least one viscosifier selected from the group consisting of: a biopolymer, cellulose, a cellulose derivative, guar, and any guar derivative.

5. The method of claim 4 wherein the biopolymer is xanthan or succinoglycan.

6. The method of claim 4 wherein the cellulose derivative is hydroxyethylcellulose.

7. The method of claim 4 wherein the guar derivative is hydroxypropyl guar.

8. The method of claim 1 wherein the step of permitting the well drill-in and servicing fluid to establish a filter cake in at least a portion of the well bore comprises forming the filter cake upon the face of the formation itself, upon a sand screen, or upon a gravel pack.

9. The method of claim 1 wherein the base fluid is present in the well drill-in and servicing fluid in an amount in the range of from about 20% to about 99.99% by volume.

10. The method of claim 1 wherein the viscosifier is present in the well drill-in and servicing fluid in an amount sufficient to provide a desired degree of solids suspension.

11. The method of claim 1 wherein the viscosifier is present in the well drill-in and servicing fluid in an amount in the range of from about 0.2% to about 0.6% by weight.

12. The method of claim 1 wherein the fluid loss control additive is present in the well drill-in and servicing fluid in an amount sufficient to provide a desired degree of fluid loss control.

13. The method of claim 1 wherein the fluid loss control additive is present in the well drill-in and servicing fluid in an amount in the range of from about 0.01% to about 3% by weight.

14. The method of claim 1 wherein the bridging agent comprises at least one bridging agent selected from the group consisting of: calcium carbonate, a magnesium compound, a chemically bonded ceramic bridging agent, and any derivative thereof.

15. The method of claim 1 wherein the bridging agent is present in the well drill-in and servicing fluid in an amount sufficient to create an efficient filter cake.

16. The method of claim 1 wherein the bridging agent is present in the well drill-in and servicing fluid in an amount in the range of from about 0.1% to about 32% by weight.

17. The method of claim 1 wherein the delayed-release acid component further comprises at least one acid derivative selected from the group consisting of: an ester; an aliphatic polyester; a lactide; a poly(lactide); a glycolide; a poly(glycolide); a lactone; a poly(.epsilon.-caprolactone); a poly(hydroxybutyrate); an anhydride; a poly(anhydride); a poly(amino acid); an esterase enzyme; and any derivative thereof.

18. The method of claim 1 wherein the delayed-release acid component comprises a blend of poly(lactic acid) and an ortho ester.

19. The method of claim 1 wherein the initiator component comprises at least one component selected from the group consisting of lactate oxidase and any derivative thereof.

20. The method of claim 1 wherein using a well drill-in and servicing fluid to drill a well bore in a subterranean formation comprises circulating the well drill-in and servicing fluid through a drill pipe and drill bit in contact with the formation.

21. The method of claim 1 wherein permitting the filter cake to degrade at a desired time comprises: allowing the delayed-release acid component to release an acid; allowing the initiator component to interact with the released acid to produce hydrogen peroxide; allowing the released acid to degrade at least a portion of the inorganic portion of the filter cake after a desired delay; and allowing the hydrogen peroxide to degrade at least a portion of the organic portion of the filter cake.

22. A method of degrading a filter cake in a subterranean formation, the filter cake comprising an inorganic portion and an organic portion, and having been established in the formation by a well drill-in and servicing fluid that comprises a delayed-release acid component, the method comprising: permitting the delayed-release acid component to release an acid, wherein the delayed-release acid component comprises at least one component selected from the group consisting of an ortho ester and a poly(ortho ester), wherein the delayed-release acid component is present in the well drill-in and servicing fluid in an amount in the range of from about 1% to about 40% by weight; contacting the filter cake with an initiator component separate from the well drill-in and servicing fluid; permitting the initiator component to interact with the released acid to produce an oxidizer; allowing the released acid to degrade at least a portion of the inorganic portion of the filter cake; and allowing the oxidizer to degrade at least a portion of the organic portion of the filter cake.

23. The method of claim 22 wherein the initiator component comprises lactate oxidase.

24. The method of claim 22 wherein the oxidizer comprises hydrogen peroxide.

25. The method of claim 22 wherein the delayed-release acid component further comprises at least one acid derivative selected from the group consisting of: an ester; an aliphatic polyester; a lactide; a poly(lactide); a glycolide; a poly(glycolide); a lactone; a poly(.epsilon.-caprolactone); a poly(hydroxybutyrate); an anhydride; a poly(anhydride); a poly(amino acid); an esterase enzyme; and any derivative thereof.

26. The method of claim 22 wherein the delayed-release acid component comprises a blend of poly(lactic acid) and an ortho ester.

Description

BACKGROUND

The present invention relates to subterranean treatment operations, and more particularly, to methods of degrading filter cakes in subterranean formations.

Often, once drilling of a well bore in a subterranean formation has been initiated, a fluid referred to as a "well drill-in and servicing fluid" may be employed. As referred to herein, the term "well drill-in and servicing fluid" will be understood to mean a fluid placed in a subterranean formation, such as those from which production has been, is being, or may be cultivated. For example, an operator may begin drilling a subterranean borehole using a drilling fluid, cease drilling at a depth just above that of a productive formation, circulate a sufficient quantity of a well drill-in and servicing fluid through the bore hole to completely flush out the drilling fluid, then proceed to drill into the desired formation using the well drill-in and servicing fluid. Well drill-in and servicing fluids often may be utilized, inter alia, to minimize damage to the permeability of such formations.

Well drill-in and servicing fluids may include "fluid-loss-control fluids." As referred to herein, the term "fluid-loss-control fluid" will be understood to mean a fluid designed to form a filter cake onto a screen or gravel pack, or in some cases, directly onto the formation. For example, a fluid-loss-control fluid may comprise a comparatively small volume of fluid designed to form a filter cake so as to plug off a "thief zone" (e.g., a formation, most commonly encountered during drilling operations, into which the drilling fluid may be lost). Generally, well drill-in and servicing fluids are designed to form a fast and efficient filter cake on the walls of a well bore within a producing formation to minimize leak-off and damage. The filter cake often comprises an inorganic portion (e.g., calcium carbonate), and an organic portion (e.g., starch and xanthan). The filter cake generally is removed before hydrocarbons from the formation are produced. Conventional methods of removal have involved contacting the filter cake with one or more subsequent fluids.

Other conventional methods of removing the filter cake include formulating the well drill-in and servicing fluid so as to include an acid-soluble particulate solid bridging agent. The resultant filter cake formed by such well drill-in and servicing fluid then is contacted with a strong acid to ultimately dissolve the bridging agent. This method is problematic, however, because the strong acid often corrodes metallic surfaces of completion equipment (e.g., sand control screens), thereby causing such equipment to prematurely fail. Further, the strong acid may damage the producing formation. Additionally, the strong acid may cause the bridging agent to dissolve prematurely, resulting in the loss of the strong acid into the formation, before it can completely cover the filter cake.

Another method of filter cake removal has involved the use of a water-soluble particulate solid bridging agent in the well drill-in and servicing fluid, which bridging agent subsequently is contacted with an aqueous salt solution that is undersaturated with respect to such bridging agent. This method is problematic, however, because such bridging agents may require a relatively long period of time to dissolve in the aqueous salt solution, due to, inter alia, the presence of various gelling agents in the well drill-in and servicing fluids. Such gelling agents may prevent the aqueous salt solution from contacting the water-soluble bridging agents.

Operators also have attempted to remove the filter cake by contacting it with a combination of an acid and an oxidizer. The acid may be used to degrade the inorganic portion of the filter cake, while the oxidizer may be employed to degrade the organic portion. However, this may be unnecessarily expensive, as it involves placement of additional components into the formation, at additional cost. For example, operators have attempted to remove the filter cake by flowing a solution comprising hydrogen peroxide into the well bore and permitting it to contact the filter cake. This may be problematic, however, as the transportation, storage, and handling of hydrogen peroxide may present safety concerns.

SUMMARY

The present invention relates to subterranean treatment operations, and more particularly, to methods of degrading filter cakes in subterranean formations.

An example of a method of the present invention is a method of drilling a well bore in a subterranean formation, comprising: using a well drill-in and servicing fluid to drill a well bore in a subterranean formation, the well drill-in and servicing fluid comprising a base fluid, a viscosifier, a fluid loss control additive, a bridging agent, and a delayed-release acid component; permitting the well drill-in and servicing fluid to establish a filter cake in at least a portion of the well bore; contacting the filter cake with an initiator component; and permitting the filter cake to degrade at a desired time. In certain embodiments of the present invention, the filter cake may be formed upon the face of the formation itself, upon a sand screen, or upon a gravel pack. Inter alia, the well drill-in and servicing fluid may be circulated through a drill pipe and drill bit in contact with the subterranean formation, in certain embodiments of the present invention.

Another example of a method of the present invention is a method of degrading a filter cake in a subterranean formation, the filter cake comprising an inorganic portion and an organic portion, and having been established in the formation by a well drill-in and servicing fluid that comprises a delayed-release acid component, the method comprising: permitting the delayed-release acid component to release an acid; contacting the filter cake with an initiator component; permitting the initiator component to interact with the released acid to produce an oxidizer; allowing the released acid to degrade at least a portion of the inorganic portion of the filter cake; and allowing the oxidizer to degrade at least a portion of the organic portion of the filter cake.

An example of a composition of the present invention is a well drill-in and servicing fluid comprising: a base fluid; a viscosifier; a fluid loss control additive; a bridging agent; and a delayed-release acid component.

The features and advantages of the present invention will be readily apparent to those skilled in the art upon a reading of the description of the embodiments which follows.

DETAILED DESCRIPTION

The present invention relates to subterranean treatment operations, and more particularly, to methods of degrading filter cakes in subterranean formations.

Certain embodiments of the methods of the present invention comprise degrading a filter cake in a subterranean formation by reacting an initiator component with a delayed-release acid component that may be present in the filter cake. In certain embodiments of the present invention, the filter cake has been established in the subterranean formation by a well drill-in and servicing fluid of the present invention generally comprising a base fluid, a viscosifier, a fluid loss control additive, a bridging agent, and a delayed-release acid component.

The base fluid utilized in the well drill-in and servicing fluids of the present invention may be aqueous-based, non-aqueous-based, or mixtures thereof. Where the base fluid is aqueous-based, the base fluid may comprise fresh water, salt water (e.g., water containing one or more salts dissolved therein), brine (e.g., saturated salt water), or seawater. Generally, the water can be from any source provided that it does not contain an excess of compounds that may adversely affect other components in the well drill-in and servicing fluid. Where the base fluid is non-aqueous-based, the base fluid may comprise any number of organic fluids. Examples of suitable organic fluids include, but are not limited to, mineral oils, synthetic oils, esters, and the like, and derivatives thereof. Generally, these organic fluids may be referred to generically as "oils." Generally, any oil in which a water solution of salts can be emulsified may be suitable for use as a non-aqueous-based base fluid in the well drill-in and servicing fluids of the present invention. Generally, the base fluid may be present in an amount sufficient to form a pumpable well drill-in and servicing fluid. More particularly, the base fluid typically is present in the well drill-in and servicing fluids of the present invention in an amount in the range of from about 20% to about 99.99% by volume of the well drill-in and servicing fluid.

The well drill-in and servicing fluids of the present invention further comprise a viscosifier. Examples of suitable viscosifiers include, inter alia, biopolymers (e.g., xanthan and succinoglycan), cellulose, cellulose derivatives (e.g., hydroxyethylcellulose), guar, and guar derivatives (e.g., hydroxypropyl guar). In certain embodiments of the present invention, the viscosifier is guar. Commercially available examples of suitable viscosifiers include, but are not limited to, those that are available from Halliburton Energy Services, Inc., of Duncan, Okla., under the trade name "N-VIS." Generally, the viscosifier is present in the well drill-in and servicing fluids of the present invention in an amount sufficient to provide a desired degree of solids suspension. More particularly, the viscosifier may be present in the well drill-in and servicing fluids of the present invention in an amount in the range of from about 0.01% to about 1.0% by weight. In certain embodiments, the viscosifier is present in the well drill-in and servicing fluids of the present invention in an amount in the range of from about 0.2% to about 0.6% by weight.

The well drill-in and servicing fluids of the present invention further comprise a fluid loss control additive. A variety of fluid loss control additives can be included in the well drill-in and servicing fluids of the present invention, including, inter alia, polysaccharides and derivatives thereof. Examples of suitable fluid loss control additives include, inter alia, starch, starch ether derivatives, hydroxyethylcellulose, cross-linked hydroxyethylcellulose, and mixtures thereof. In certain embodiments, the fluid loss control additive is starch. Commercially available examples of suitable fluid loss control additives include, but are not limited to, those that are available from Halliburton Energy Services, Inc., of Duncan, Okla., under the trade name "N-Dril HT PLUS." The fluid loss control additive generally is present in the well drill-in and servicing fluids of the present invention in an amount sufficient to provide a desired degree of fluid loss control. More particularly, the fluid loss control additive may be present in the well drill-in and servicing fluids of the present invention in an amount in the range of from about 0.01% to about 3% by weight. In certain embodiments, the fluid loss control additive is present in the well drill-in and servicing fluids of the present invention in an amount in the range of from about 1% to about 2% by weight.

The well drill-in and servicing fluids of the present invention further comprise a bridging agent. The well drill-in and servicing fluids of the present invention suspend the bridging agent and, as the well drill-in and servicing fluids begin to form a filter cake within the subterranean formation, the bridging agent becomes distributed throughout the resulting filter cake, most preferably uniformly. In certain embodiments of the present invention, the filter cake may form upon the face of the formation itself, upon a sand screen, or upon a gravel pack. In certain embodiments of the present invention, the bridging agent comprises, inter alia, calcium carbonate, a magnesium compound (e.g., magnesium oxide), or a chemically bonded ceramic bridging agent, or derivatives thereof. Generally, the bridging agent is present in the well drill-in and servicing fluids of the present invention in an amount sufficient to create an efficient filter cake. As referred to herein, the term "efficient filter cake" will be understood to mean a filter cake comprising no material beyond that required to provide a desired level of fluid loss control. In certain embodiments of the present invention, the bridging agent is present in the well drill-in and servicing fluids of the present invention in an amount ranging from about 0.1% to about 32% by weight. In certain embodiments of the present invention, the bridging agent is present in the well drill-in and servicing fluids of the present invention in the range of from about 3% and about 10% by weight. In certain embodiments of the present invention, the bridging agent is present in the well drill-in and servicing fluids of the present invention in an amount sufficient to provide a fluid loss of less than about 15 mL in tests conducted according to the procedures set forth by API Recommended Practice (RP) 13.

The well drill-in and servicing fluids of the present invention further comprise a delayed-release acid component. When the well drill-in and servicing fluids of the present invention have been formulated and placed within the subterranean formation, the delayed-release acid component releases an acid (e.g., lactic acid), as illustrated in Equation 1 below:

.times..times..times..times..times..times..times..times..times..times. .times..times..times..times..times..times..times..fwdarw..times..times..t- imes..times. .times..times. ##EQU00001## The optional catalyst may be present within the well drill-in and servicing fluids of the present invention, or may be placed in the well bore separately. The optional catalyst may comprise an acid, or a base. One of ordinary skill in the art, with the benefit of this disclosure, will recognize when the use of an optional catalyst may be appropriate for a particular application, and whether such optional catalyst should comprise an acid or a base.

The released acid reacts with the initiator component to produce an oxidizer, as illustrated in Equation 2 below:

.times..times..times..times..times..times..times..times..times..times..fw- darw..times..times..times..times. ##EQU00002## In certain embodiments of the present invention, the oxidizer produced may be, inter alia, hydrogen peroxide. In certain embodiments of the present invention, one or more byproducts may be produced by the reaction between the released acid and the initiator component. For example, when the released acid comprises lactic acid, and the initiator component comprises lactate oxidase, the reaction between lactic acid and lactate oxidase may produce an oxidizer (e.g., hydrogen peroxide) and a byproduct (e.g., pyruvic acid). Accordingly, the compositions and methods of the present invention are capable of producing an oxidizer while within the subterranean formation, thereby eliminating or reducing certain safety concerns that may be present in conventional operations, e.g., safety concerns that accompany the storage, transportation, and handling of oxidizers that are injected into the formation from the surface.

In addition to reacting with the initiator component, the released acid also may react with the inorganic portion of the filter cake, as illustrated in Equation 3 below:

.times..times..times..times..times..times. .times..times..times..times..times..times..times..times..times..times..fw- darw..times..times..times..times. .times..times..times. ##EQU00003## For example, where the inorganic portion of the filter cake comprises calcium carbonate, and where the released acid comprises lactic acid, the reaction product may comprise calcium lactate. As another example, where the inorganic portion of the filter cake comprises magnesium oxide, and where the released acid comprises lactic acid, the reaction product may comprise magnesium lactate.

The rate at which the released acid is released by the delayed-release acid component, "k1," inter alia, may largely determine the total degradation time of the inorganic portion of the filter cake (though, as will be described further with reference to "k2," the total degradation time of the inorganic portion of the filter cake may be delayed, inter alia, by the presence and amount of an initiator component). Generally, k1 depends on factors such as, inter alia, the time during which water and the delayed release acid component are permitted to contact each other, the amount of water that is available to react with the delayed release acid component, temperature, and the presence or absence of the optional catalyst. Generally, both acid catalysts and base catalysts may be used to increase k1. In certain embodiments of the present invention, the reaction depicted in Equation 1 may be base-catalyzed, and caustic may be used as the optional catalyst.

The reaction rate between the initiator component and the released acid, "k2," inter alia, determines the extent to which the reaction between the released acid and the inorganic portion of the filter cake may be delayed. Furthermore, the oxidizer produced by the reaction of the released acid with the initiator component may degrade the organic portions of a filter cake that has been established in a subterranean formation by the well drill-in and servicing fluid. In certain embodiments of the present invention, k2 may be increased by permitting the reaction to occur in the presence of an oxygen source (e.g., by bubbling oxygen into the region of the subterranean formation where the reaction is occurring). In certain embodiments of the present invention, k2 may be decreased by the placement of a temporary physical barrier between the initiator component and the released acid, e.g., by encapsulating the initiator component in a suitable encapsulant, which encapsulant may be selected to degrade within the subterranean formation at a desired time. Examples of suitable encapsulants for the initiator component may include, inter alia, fatty acids, and the like.

The delayed-release acid components generally comprise an acid derivative. Examples of suitable acid derivatives include, but are not limited to: esters, such as ortho esters; poly(ortho esters); aliphatic polyesters; lactides, poly(lactides); glycolides; poly(glycolides); lactones; poly(.epsilon.-caprolactones); poly(hydroxybutyrates); anhydrides; poly(anhydrides); and poly(amino acids). The delayed-release acid components also may comprise an esterase enzyme (e.g., proteinase-K), if desired. In certain embodiments of the present invention, the esterase enzyme may be encapsulated by means known in the art. Blends of certain acid-releasing degradable materials also may be suitable. One example of a suitable blend of materials includes a blend of a poly(lactic acid) and an ortho ester. It is within the ability of one skilled in the art, with the benefit of this disclosure, to select a suitable acid-releasing degradable material. When used in the present invention, a desirable result may be achieved if the acid-releasing degradable material degrades slowly over time, as opposed to instantaneously.

In certain embodiments of the present invention, the delayed-release acid components may comprise a mixture of an acid derivative and a hydrated organic or inorganic solid compound. For example, in circumstances wherein an insufficient amount of water is present in the subterranean formation to facilitate the degradation of the acid derivative, a desirable choice for a delayed-release acid component may comprise a mixture of an acid derivative and a hydrated organic or inorganic solid compound. In an embodiment of the present invention, the acid derivative may degrade in the water provided by the hydrated organic or inorganic compound, which dehydrates over time when heated in the subterranean zone. Examples of such hydrated organic or inorganic compounds may include, but are not limited to: sodium acetate trihydrate; L-tartaric acid disodium salt dihydrate; sodium citrate dihydrate; sodium tetraborate decahydrate; sodium hydrogen phosphate heptahydrate; sodium phosphate dodecahydrate; amylose; starch-based hydrophilic polymers; or cellulose-based hydrophilic polymers.

The delayed-release acid components generally may be present in the well drill-in and servicing fluids of the present invention in an amount sufficient to release a desired amount of acid. In certain embodiments of the present invention, the desired amount of acid that will be released is an amount that will: (1) react with an initiator component to produce a desired amount of an oxidizer; and (2) degrade at least a portion of the inorganic component of the filter cake. The oxidizer produced by the reaction between the initiator component and the released acid may degrade the organic portions of a filter cake that has been established in a subterranean formation by, inter alia, a well drill-in and servicing fluid. In certain embodiments of the present invention, the delayed-release acid component may be present in the well drill-in and servicing fluids of the present invention in an amount in the range of from about 1% to about 40% by weight. In certain embodiments of the present invention, the delayed-release acid component may be present in the well drill-in and servicing fluids of the present invention in an amount in the range of from about 5% to about 20% by weight.

In accordance with certain embodiments of the methods of the present invention, an initiator component may be placed in the subterranean formation at a desired time, so as to contact, and react with, an acid released by the delayed-release acid component (that may be present in a well drill-in and servicing fluid of the present invention), to thereby produce an oxidizer. Examples of suitable initiator components include, inter alia, enzymes such as lactate oxidase, and the like. Generally, the amount of initiator component required is an amount sufficient to: (1) delay, for a desired period of time, the interaction between the inorganic portion of the filter cake and the acid released by the delayed-release acid component; and (2) produce a sufficient amount of an oxidizer (e.g., a peroxide such as hydrogen peroxide) when reacting with the released acid to ultimately degrade at least a portion of the organic portion of the filter cake. In certain embodiments of the present invention, the amount of the initiator component that may be placed in the subterranean formation may be an amount in the range of from about 0.0005% to about 0.01% by weight of the delayed-release acid component. In certain embodiments of the present invention, the amount of the initiator component that may be placed in the subterranean formation may be an amount in the range of from about 0.001% to about 0.002% by weight of the delayed-release acid component. For example, where the delayed-release acid component is poly(lactic acid) and the initiator component is lactate oxidase, the initiator component may be added in a ratio of 2 milligrams of lactate oxidase per 1 gram of poly(lactic acid). In certain embodiments of the present invention where an operator desires a long delay of the interaction between the released acid and the inorganic portion of the filter cake, the operator may elect to increase the amount of the initiator component. However, the particular acid-derivative component of the delayed-release acid composition, the particular components of the filter cake, and any other components present in the well bore (e.g., other acids) may dictate the appropriate amount to include. Also, the desired delay period for degrading the filter cake should be considered in deciding upon the appropriate relative concentrations of the delayed-release acid component and the initiator component. One of ordinary skill in the art, with the benefit of this disclosure, will recognize the appropriate amount of each component to include for a desired application.

Generally, the initiator component interacts with acids present in the well bore (e.g., the acid released by the delayed-release acid component) in such a way as to delay the interaction between at least a portion of the acids and at least a portion of the inorganic portion of the filter cake for a period of time, thereby delaying degradation of the inorganic portion of the filter cake by the acid. Thus, the integrity of the filter cake may not be jeopardized for a given desired delay period. Degradation of only a very small percentage of the inorganic portion of the filter cake (e.g., less than about 2%) may compromise the integrity of the filter cake. The reaction between the initiator component and the released acid also generates an oxidizer (e.g., a peroxide) that ultimately may degrade the organic portion of the filter cake. In certain embodiments, the oxidizer may be, inter alia, hydrogen peroxide and/or pyruvate. The oxidizer then may interact with the organic portion of the filter cake to ultimately degrade at least a portion of the organic portion of the filter cake.

An example of a composition of the present invention is a well drill-in and servicing fluid comprising 78.5% water by weight, 7.9% sodium chloride by weight, 0.2% N-VIS by weight, 1.7% N Dril HT PLUS by weight, 7.0% poly(lactic acid) by weight, and 4.7% calcium carbonate by weight.

An example of a method of the present invention is a method of drilling a well bore in a subterranean formation, comprising: using a well drill-in and servicing fluid to drill a well bore in a subterranean formation, the well drill-in and servicing fluid comprising a base fluid, a viscosifier, a fluid loss control additive, a bridging agent, and a delayed-release acid component; permitting the well drill-in and servicing fluid to establish a filter cake in at least a portion of the well bore; contacting the filter cake with an initiator component; and permitting the filter cake to degrade at a desired time. In certain embodiments of the present invention, the filter cake may be formed upon the face of the formation itself, upon a sand screen, or upon a gravel pack. Inter alia, the well drill-in and servicing fluid may be circulated through a drill pipe and drill bit in contact with the subterranean formation, in certain embodiments of the present invention.

Another example of a method of the present invention is a method of degrading a filter cake in a subterranean formation, the filter cake comprising an inorganic portion and an organic portion, and having been established in the formation by a well drill-in and servicing fluid that comprises a delayed-release acid component, the method comprising: permitting the delayed-release acid component to release an acid; contacting the filter cake with an initiator component; permitting the initiator component to interact with the released acid to produce an oxidizer; allowing the released acid to degrade at least a portion of the inorganic portion of the filter cake; and allowing the oxidizer to degrade at least a portion of the organic portion of the filter cake.

An example of a composition of the present invention is a well drill-in and servicing fluid comprising: a base fluid; a viscosifier; a fluid loss control additive; a bridging agent; and a delayed-release acid component.

Therefore, the present invention is well adapted to carry out the objects and attain the ends and advantages mentioned as well as those that are inherent therein. While the invention has been described with reference to embodiments of the invention, such a reference does not imply a limitation on the invention, and no such limitation is to be inferred. The invention is capable of considerable modification, alternation, and equivalents in form and function, as will occur to those ordinarily skilled in the pertinent arts and having the benefit of this disclosure. The described embodiments of the invention are exemplary only, and are not exhaustive of the scope of the invention. Consequently, the invention is intended to be limited only by the spirit and scope of the appended claims, giving full cognizance to equivalents in all respects.

* * * * *